You may have noticed the vaguely menacing tone of recent government advertising campaigns. Here is a current example: 'If you know a business that isn't registered for tax, call the Revenue or HM Customs - no names needed.' Another says: 'Technology has made it easier to identify benefit cheats.'

Whether the campaign is about rape, TV licences or filling in your tax form, there is always a we-know-where-you-live edge to the message, a sense that this government is dividing the nation into suspects and informers.

Reading the Identity Cards Bill, as it pinged between the House of Commons and the Lords last week, I wondered about the type of campaign that will be used to persuade us to comply with the new ID card law. Clearly, it would be orchestrated by some efficient martinet like the Minister of State at the Home Office, Hazel Blears. Her task will be to put the fear of God into the public at the same time as reassuring us that the £90 cost of each card will protect everyone from identity theft, terrorism and benefit fraud.

The ads might imagine any number of scenarios. Here is one. 'Your elderly mother has fallen ill,' starts the commentary gravely. 'You travel from your home to look after her. She has a chronic condition but this time, it's a bit of a crisis and you need to pick up a prescription at the only late-night chemist in town. Trouble is, she has mislaid her identity card and you never thought to get one. Under the new law, the pharmacist will not be able to give you that medicine without proper ID. So, get your card. It's for your own good - and Mum's.'

It became clear last week that the government will do anything to get this bill through parliament, including ignoring its own manifesto pledge to make the cards voluntary, a fact that we should remember as each of us entrusts the 49 separate pieces of personal information to a national database. By the end of last year, the government had already spent £32m of taxpayers' money on the scheme and, at the present, the expenditure is edging towards £100,000 a day. No surprise that Home Secretary Charles Clarke dissembles about Labour promises.

Labour's manifesto said: 'We will introduce ID cards, including biometric data like fingerprints, backed up by a national register and rolling out initially on a voluntary basis as people renew their passports.'

It turns out that there is nothing voluntary about it. If you renew your passport, you will be compelled to provide all the information the state requires for its sinister data base. The Home Secretary says that the decision to apply for, or renew, a passport is entirely a matter of individual choice; thus he maintains that the decision to commit those personal details to the data base is a matter of individual choice.

George Orwell would have been pleased to have invented that particular gem. Yet this is not fiction, but the reality of 2006, and we should understand that if the Home Secretary is prepared to mislead on the fundamental issue as to whether something is voluntary or compulsory, we cannot possibly trust his word on the larger issues of personal freedom and the eventual use of the ID card database.

Clarke has now established himself as a deceiver, even in the eyes of his party. Labour democrats such as Kate Hoey, Diane Abbott, Bob Marshall-Andrews and Mark Fisher all understood that the Lords' amendments of last week simply sought to underline this concept of a voluntary scheme, which complied with the 2005 manifesto. Oddly enough, the compulsory provision of personal information to the government database is not the greatest threat to our freedom, though it is in itself a substantial one. The real menace comes when the ID card scheme begins to track everyone's movements and transactions, the details of which will kept on the database for as long as the Home Office desires.

Over the past few weeks, an anonymous email has been doing a very good job of enlightening people on how invasive the ID card will be. 'Private businesses,' says the writer, 'are going to be given access to the national identity register database. If you want to apply for a job, you will have to present your card for a swipe. If you want to apply for a London underground Oystercard or supermarket loyalty card or driving licence, you will have to present your card.'

You will need the card when you receive prescription drugs, when you withdraw a relatively small amount of money from a bank, check into hospital, get your car unclamped, apply for a fishing licence, buy a round of drinks (if you need to prove you're over 18), set up an internet account, fix a residents' parking permit or take out insurance.

Every time that card is swiped, the central database logs the transaction so that an accurate plot of your life is drawn. The state will know everything that it needs to know; so will big corporations, the police, the Inland Revenue, HM Customs, MI5 and any damned official or commercial busybody that wants access to your life. The government and Home Office have presented this as an incidental benefit, but it is at the heart of their purpose.

Last week, Andrew Burnham, a junior minister at the Home Office, confirmed the anonymous email by admitting that the ID card scheme would now include chip-and-pin technology because it would be a cheaper way of checking each person's identity. The sophisticated technology on which this bill was sold will cost too much to operate, with millions of checks being made every week.

That is a very important admission because the government still maintains the fiction that the ID card is defence against identity theft and terrorism. The 7 July bombers would not have been deterred by a piece of plastic. And it is clear that the claim about protecting your identity is also rubbish because chip-and-pin technology has already been compromised by organised criminals. What remains is the ceaseless monitoring of people's lives. That is what the government is forcing on us.

Practically every week in these columns, I urge you to pay attention to the government's theft of our liberties. I would feel a bore and an obsessive if I hadn't pored over the ID card bill last week and read Hansard's account of the exchanges in both houses. One of the most chilling passages in the bill is section 13 which deals with the 'invalidity and surrender' of ID cards, which, in effect, describes the withdrawal of a person's identity by the state. For, without this card, it will be almost impossible to function, to exist as a citizen in the UK. Despite the cost to you, this card will not be your property.

People keep asking me what they can do about the lurch into Labour's velvet tyranny and I keep replying that the only way for us is to re-engage with the politics of our country. But it is difficult. The new Conservative regime under David Cameron has not yet found the voice to articulate the objection to the radical changes proposed in our society. Edward Garnier, the Tory spokesman on ID cards, did his best in the Commons last week, but we need to hear his leader express the principled outrage that comes from conviction and unyielding values. If we don't, we may justifiably wonder if the Conservatives are sitting on their hands in the belief that they will eventually inherit Labour's apparatus of control.

Outside parliament, what needs to happen is the formation of the broadest possible front against these changes, a movement which deploys the most principled democratic minds in the country to argue with the lazy and stupid view that if you've got nothing to hide, you have nothing to fear from Labour's attack on liberty. I believe that will happen.

henry.porter@observer.co.uk